System Description
The Trident® Ceramic Acetabular System is
an artificial hip replacement device that features a
new, state-of-the-art ceramic-on-ceramic bearing couple.
The artificial hip replacement device consists of four
basic components: an alumina ceramic insert (socket
liner), an alumina ceramic femoral head (ball), a metal
acetabular shell (socket), and a metal femoral stem (hip
stem).
The hip stem is inserted into the top of the
thighbone. The ball fits onto the top of the hip stem.
The socket liner and mating socket are fixed to the hip
joint. The ball and socket articulate together.
The Trident® implant has bearing surfaces
(the ball and socket) made of alumina ceramic.
Laboratory testing of alumina ceramic has shown it to
have less wear than the metal and plastic materials that
are currently used in total hip surgery. Alumina ceramic
is extremely hard in fact, its hardness is second only
to diamond and provides excellent lubrication between
the ball and socket. Because of its material
characteristics, alumina ceramic-on-ceramic demonstrates
significantly lower wear versus conventional
metal-on-plastic components in laboratory testing.
Therefore, it is anticipated that these improved wear
characteristics will extend the life of the implants.
Purpose of the Device
This total hip replacement is indicated for patients
with painful, disabling hip joint disease caused by a
severe form of arthritis.
This total hip replacement should not be used for
patients:
-
Who may have an infection in or near the hip
joint,
-
Who are unable to comply with the instructions
for preparing for and recovering from the surgery,
-
Who do not have enough healthy bone to support
fixation of the implants, or
-
Whose bones are not fully grown.
Clinical Experience
Howmedica Osteonics Corp. (hereafter referred to as
Stryker Orthopaedics) conducted a clinical study in the
United States for its ceramic-on-ceramic hip system,
which was conducted under a study protocol approved by
the United States Food and Drug Administration. The
study was performed at 16 orthopaedic centers of
excellence across the United States. The clinical study
was conducted for Stryker Orthopaedics first generation
ceramic-on-ceramic design (called the ABC System), and
second generation ceramic-on-ceramic design (called the
Trident® System). In all, the data from 558
hip replacement surgeries (cases) with these
ceramic-on-ceramic bearings were evaluated.
How do I know if the Trident®
Ceramic System is right for me?
The prospective, randomized, clinical study began in
1996, with 349 cases with the first-generation
ceramic-on-ceramic systems, and 165 cases with a control
device (conventional, metal-on-polyethylene). The
clinical data on these cases were evaluated out to 24
months (2 years) after surgery. In 1999, the patented
Trident® Ceramic System was then entered into
the study. This patented design offers a stronger,
easier-to-use ceramic liner design. Two hundred nine
(209) Trident® inserts were implanted in the
study. The clinical data from these cases has also been
evaluated out to 24 months (2 years) after surgery.
The Trident® System features the identical
ceramic-on-ceramic articulating bearing surface as the
ABC System; however, the Trident® system
features an outer titanium sleeve. The titanium sleeve
offers the following unique advantages over other first
generation ceramic-on-ceramic designs:
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Increases the strength of the ceramic insert by
50%: The Trident® Alumina Insert is the
strongest ceramic insert on the U.S. market today,
-
Protects the insert rim from chipping during
implant assembly: Occasional chipping of the insert
rim during surgery was reported during clinical
studies of first-generation designs. No Trident®
ceramic implants chipped or fractured in the study.
-
Allows reassembly of the acetabular shell to the
insert: First-generation designs prohibit reassembly
of a ceramic insert to its shell, making insert
adjustment or replacement more difficult.
Safety Data
Safety of the ceramic-on-ceramic hip systems was
established by studying the adverse (unfavorable) events
within the clinical study. The adverse events
experienced by patients who received the
ceramic-on-ceramic hip systems (test group) were
comparable to the adverse events experienced by patients
who received a conventional, metal-on-polyethylene hip
system (control group). There were no deaths in the test
or control study groups. Additional surgery to replace
or remove components occurred 4 times in the Trident®
ceramic-on-ceramic group, as compared to 5 times in the
metal-on-poly (control group). Analysis of the adverse
event data demonstrated that there was no significant
difference between the adverse events experienced in the
test and control groups.
Effectiveness Data
The effectiveness of the Trident®
ceramic-on-ceramic systems was established by comparing
the Harris Hip Scores (HHS) and the radiographic (X-ray)
measurements of patients who received the
ceramic-on-ceramic systems to those of patients who
received the metal-on-polyethylene (control) hip system.
Pain and Function Improvement:
The Harris Hip Score is a scale from 1-100 that
assesses a patient’s level of pain and function. The
highest possible score (100) indicates pain relief and
normal functional ability. The lowest possible score (0)
indicates severe pain and disability. A score of 90-100
is considered excellent. At two years after surgery, the
average Harris Hip Scores for the ceramic-on-ceramic
group and for the control group were both in the
excellent range.
X-ray (Radiographic) Measurements:
X-rays were reviewed at regular intervals after surgery
to look for signs of possible device loosening, device
movement, or accelerated wearing away of the components.
At two years after surgery, all of the 185 Trident®
cases evaluated were considered a radiographic success.
No devices showed signs of device loosening, device
movement, or accelerated wearing away of the components.
Patient Success Rates:
A patient was considered a success within the study if,
at two years after surgery, the hip implant system was
still in place (had not been replaced), the Harris Hip
Score was greater than 70 points, and there were no
x-ray signs that might indicate loose or unstable hip
implant components. The patient success rate for the
control group was 94%. The patient success rate for the
Trident® ceramic-on-ceramic group was 97%.
Use for Inflammatory Joint
Disease
The study results presented above include only
patients who had primary total hip replacement for
severe, non-inflammatory degenerative joint disease.
Eight additional cases of inflammatory joint disease
were enrolled in the study, and received a
ceramic-on-ceramic system (either ABC or Trident®).
The eight cases have been followed for a mean duration
of 16 months. As of the latest functional evaluations,
the mean HHS is 94 (range 85-100). There have been no
reoperations or revisions. There have been no
operative-hip-related complications. All components
appear stable on X-ray.
Potential Benefits
The goals of artificial hip replacement include
relief of pain, restoration of function, and correction
of deformity. Ceramic-on-ceramic, however, demonstrates
significantly lower wear versus conventional
metal-on-plastic components in laboratory testing.
Therefore, it is anticipated that these improved wear
characteristics will result in a longer lasting implant.
Potential Risks
Any artificial hip replacement may be associated with
serious complications. These include: dislocation,
loosening, implant breakage, bone fracture, reaction to
the implant’s materials, bone loss, change in the length
of the treated leg, pain, hip stiffness, excessive
bleeding, hip joint fusion, nerve damage, allergic
reaction to medical and/or blood transfusion, infection,
reactions to pain-relieving drugs, blood clots in the
legs and/or lungs, amputation, heart attack, pneumonia,
excessive wear of the implant’s components, decrease of
bone mass, and audible sounds during motion.
With this ceramic-on-ceramic system, sudden breakage
of ceramic components resulting from excessive forces is
possible; however, no ceramic component broke during the
clinical study. Corrosion (eroding) between the insert
and shell may be possible; however, this event was not
demonstrated in the clinical study, and laboratory tests
have shown the potential to be minimal.
Any of the above-cited complications may require
medical intervention, including additional surgery. In
rare instances, complications may lead to death. Please
ask your surgeon to discuss with you any of these
complications that are not familiar to you.
Patient Instruction
Call your doctor if you experience any of the
following symptoms:
-
Redness, burning, swelling, or drainage from
your operated area
-
Fever of 100 degrees or higher
-
Pain that does not lessen with rest
-
Acute, severe pain in the hip associated with
twisting, turning or injury
Consult your doctor regarding considerations before
surgery, rehabilitation after surgery, and expectations
for surgery. It is important to begin planning for your
return home from the hospital before your surgical
procedure. Your surgeon may suggest tips to prepare your
home for after surgery. For example, get an apron or
belt with pockets to carry things while you are on
crutches, buy or borrow a cordless phone, remove scatter
rugs and other obstacles to safe transport using
crutches, have high chair and commode accessories
available. Above all, during this time, treat yourself
well, eat balanced meals, get plenty of rest, and if
requested by your surgeon, donate your own blood so it
can be transfused during and after surgery.
After surgery you will need to rest your hip to allow
proper healing. Your activity will be restricted during
this healing period. During the first weeks after
surgery, you may be advised to put a pillow between your
legs when turning over in bed, wear elastic stockings,
use raised toilet seat, take showers rather than baths,
restrict activities such as sudden twisting or turning,
crossing legs, exposing the scar to sunlight, and
driving. Follow carefully your doctor’s instructions
regarding progression to normal weight bearing and
resumption of normal physical activity. Individual
results will vary and all patients will experience
different activity levels post-surgery.
Even after the healing period, excessive loads placed
on the implants through sudden trauma or high impact
activities, such as running and jumping, can damage the
artificial joint. While the expected life of an
artificial hip replacement system is difficult to
estimate, it is finite. The components are made of
foreign materials that will not indefinitely withstand
the activity level and loads of normal, healthy bone.
The hip joint may have to be replaced at some time in
the future.
Alternative Treatments
Other options may include use of a conventional hip
replacement system, other surgical procedures that do
not replace the hip joint, or non-surgical treatments
based on pain management and activity restriction. Your
doctor can explain these alternatives, and help you
decide which treatment is best for your condition.
* With 24 month follow-up on ABC
and Control Groups, and 6 month follow-up on Trident®
group.
Additional Information About Stryker Hip Products
Stryker Website
Jack Nicklaus Story
